Cellulosic fibers such as paper pulp, bagasse, insulation or fiber board materials, cotton and the like, are commonly subjected to a refining operation which consists of mechanically rubbing the fiber between sets of relatively rotating bar and groove elements. In a disk-type refiner, these elements commonly consist of plates having annularly arranged bar and groove patterns defining their working surfaces, with the bars and grooves extending generally radially of the axis of the rotating element, or more often at an angle to a radius to the center of the annular pattern, so that the stock can work its way from the center of the pattern to its outer periphery.
Disk-refiners are commonly manufactured in both single and twin disk types. In the former, the working surface of the rotor comprises an annular refiner plate, or a set of segmental refiner plates, for cooperative working action with a complementary working surface on the stator which also comprises an annular plate or a series of segmental plates forming an annulus. In a twin disk refiner, the rotor is provided with working surfaces on both sides which cooperate with a pair of opposed complementary working surfaces on the stator, with these working surfaces being of the same type of construction as with a single disk refiner. In both types of refiners, the refiner plates are expendable and must be replaced when their working pattern of bars is worn away.